The present invention relates to a circuit breaker accessory, and, more particularly, to a reset system for a circuit breaker accessory.
It is generally well known in the art of circuit breakers to provide a reset mechanism to reset a tripping device such as an accessory shunt trip or under voltage device. During quiescent operation, (i.e. when the circuit breaker contacts are closed to allow the flow of electrical current) the operating handle of an operating mechanism is in the xe2x80x9cONxe2x80x9d position. To stop the current flow manually, the handle may be shifted to the xe2x80x9cOFFxe2x80x9d position thereby opening the electrical contacts. Upon attainment of a pre-determined condition (trip event), such as ground fault or overload, the operating mechanism of the circuit breaker will release the forces of the mechanism operating springs and release the operating handle to a tripped position between the xe2x80x9cONxe2x80x9d position and the xe2x80x9cOFFxe2x80x9d position. Before the circuit breaker may be turned xe2x80x9cONxe2x80x9d, the operating mechanism must be manually reset. This is accomplished by rotating the operating handle beyond the xe2x80x9cOFFxe2x80x9d position against the bias of the operating mechanism springs, thereby locking the operating mechanism in position.
The same mechanical forces used to direct the operating mechanism from the tripped position to the reset position are used to reset any attached accessories, such as an electronic trip actuator, a shunt trip actuator, auxiliary switch accessory, bell alarm or other type of accessory unit. However, as accessories are generally separate components mounted proximate to the operating mechanism, positional variations at the interface of the accessory and the circuit breaker operating mechanism are possible due to manufacturing tolerances. These positional variations can effect the quantity of reset force translated to the accessory and the range of motion of the provided reset force.
In an exemplary embodiment of the invention, an accessory includes a trip arm biased by a spring to pivot in a clockwise direction about a trip arm pivot. A latch is arranged to pivot about a latch pivot and has the trip arm acting on a latch surface on the latch to push the latch in a counter clockwise direction about the latch pivot. An electromechanical device is positioned in the accessory having a plunger that acts on the latch by pulling it such that it is holding with the trip arm. When a signal is provided to the electromechanical device, the plunger is moved allowing the trip arm, being pushed by the stored energy spring, push the latch out of the way and interface the operating mechanism. To reset the trip arm and the latch, a reset lever is arranged to pivot about the latch pivot. The reset lever is configured to interface the operating mechanism, and has a drive portion for interfacing the trip arm for resetting. Thus, when the operating mechanism is reset, a portion extending from an operating handle interfaces the reset lever causing it to pivot, wherein the drive portion interfaces the trip arm to drive the trip arm about the trip arm pivot into the latched and ready to operate position.
This invention has many advantages over the prior art, including but not limited to the ability to reduce the quantity of reset force required to reset the accessory and to provide positional tolerance with added reset over-travel within the accessory.